1. Field of the Invention
This invention relates to an "Otto" or a "Diesel"-cycle four-stroke internal combustion engine, having one or more cylinders in any orientation. The engine is designed and structured as to be of very simple construction. The engine is capable of delivering a specific power and higher number of revolutions than prior art engines with the same cylinder capacity. The weight and cost of the engine is remarkably lower and has the advantage of lower emissions.
2. The Prior Art
As is known, the present mechanical engineering for internal combustion engines provides substantially for two types of engines, namely four-stroke engines and two-stroke engines, utilizing either the Otto or the Diesel cycle.
It is also known that four-stroke engines have many and great advantages relative to the two-stroke engine. Actually, gasoline four-stroke engines have a higher thermodynamical yield, clean emissions, lower fuel consumption and run quieter compared to two-stroke engines which utilizes a gasoline-oil mixture. All these advantages involve a greater mechanical complexity, which in practice brings about an increase in weight and higher costs.
Two-stroke engines, on the contrary, have only the advantage of being structurally simpler and of delivering greater power than is delivered by four-stroke valve engines. This is due to the fact that two-stroke engines--with the same r.p.m.s.--have twice as many active phases, i.e. explosions. The application field of two-stroke engines is substantially limited to low displacement engines, where technical simplicity, low cost and low weight prevail. Four-stroke engines, usually the multi-cylinder ones, are largely used for applications that require high power, such as motor cars, transport motor vehicles, racing cars, and in all those cases where cost, mechanical complexity and weight are largely justified by the performances of these engines.
Attempts have been made to reduce the mechanical complexity and the weight of four-stroke valve engines. However, these attempts have brought about technically and practically acceptable results, such as to justify their utilization instead of the traditional two-stroke engines.
On the other hand, the mechanical-structural complexity of four-stroke engines, however improved, for instance through the adoption of head camshafts in order to eliminate tappets, is still practically unchanged. This is due to the fact that said mechanical complexity lies especially in the complex kinematic chain which constitutes the so-called "timing system", i.e. a system consisting of two or more head valves for each cylinder, crankshafts for driving the valves either directly or through tappets, the geared kinematic chains or toothed belts which transfer the motion of the driving shaft to the crankshafts, which, in their turn, control the valves according to prefixed intervention phases to carry out the opening-closing cycle of the valves of each cylinder.
It is also well known that today internal combustion engines ("Otto" cycle, either utilizing gasoline or diesel), have the drawback of high emissions and, therefore, noxious exhaust gases, as fuel combustion is always incomplete due to the impossibility of obtaining, with the present structures of these engines, a perfect mixing in the combustion chamber between fuel and combustion supporter (oxygen from air). To obtain a perfect mix between fuel and oxygen, a mixing on a molecular level should be achieved in each space of the combustion chamber according to substantially stoichiometric ratios.
In other words, it would be necessary to cause a powerful vortical motion of the components of the mix, which cannot be achieved because of the very short time in which the mixing takes place; besides, even the vortical motion of the components of the mix, caused by the shiftings of the piston, is never sufficient to allow a perfect mixing, especially in a Diesel-cycle; this is due to the fact that movement of the piston causes vortexes of the combustion components which are always substantially axially orientated relatively to the piston skirt, which contrasts sharply with what is well known, i.e. that to obtain an ideal vortex, its axis should always be obliquely orientated relatively to the shifting direction of the members that generate the vortex. At present, in an effort to reduce air pollution caused by exhaust gases of today's engines, expensive special fuels or expensive and heavy catalytic silencers are used.
There arises, therefore, the problem of providing a one- or multi-cylinder four-stroke engine, so designed as to sharply reduce the mechanical complexity and, therefore, also the weight and cost of four-stroke engines with two or more pairs of valves per cylinder.